The present invention relates generally to driving devices intended to impart a permanent reciprocating movement to a mechanical element. More particularly, the invention relates to a device for maintaining a rectilinear or rotational oscillatory movement of an element or group of elements, such as a pump unit.
It is an object of the invention to provide a driving device of the type indicated above which through the use of simple and reliable mechanisms makes it possible to obtain a permanent reciprocating movement of which both the amplitude and the frequency can be controlled with great ease.